Crystalline organic materials possessing a polar axis have potential applications in information processing and communications fields.Previous work suggests that crystalline naphthazarin (5,8-The case of 12 is interesting because it undergoes a single crys- tal to single crystal phase change. X-ray diffraction of transformed individual crystals show retained crystallinity.dihydroxy-1,4-naphthoquinone) undergoes a rapid tautomeric exchange between 1a and 1b at room temperature.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)Upon cooling below 110(DEGREES)K, one form of naphthazarin undergoes a reversible centrosymmetric to noncentrosymmetric phase transition.This thesis reports the structures and solid state chemistry of several quinizarins.Thermally induced solid state transitions have been identified in quinizarin 2 as well as the 2,3-dichloro and 2,3-dimethyl quinizarins 11 and 12. These transitions have been characterized by differential thermal analysis, X-ray powder diffraction, FTIR spectroscopy, and laser second harmonic generation (SHG). X-ray crystal structures have been determined for two forms of 11 and one form of 12. Other quinizarins, naphthazarins, and naphthazarin esters have also beeninvestigated in the solid state, and in several cases X-ray crystal structures have been determined.(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI)The transition of 11 is unusual in that it involves a non-polar to polar phase change upon heating. The transition of 11 was charac- terized by the development of laser frequency doubling while heating a powdered sample. The powder SHG efficiency of the high tempera- ture form of 11 is more than twice that of urea (a common SHG standard).